Java crashes when calling dll function using JNA - dll

Question

I'm using JNA to run a dll function:
Here is all the code corresponding to that manner:
The Native Declarations:
//how the method declared
H264_Login (char *sIP, unsigned short wPort, char *sUserName, char *sPassword, LP_DEVICEINFO lpDeviceInfo, int *error, ，SocketStyle socketTyle=TCPSOCKET); // where LP_DEVICEINFO is a struct
//how the struct declared
typedef struct _H264_DVR_DEVICEINFO
{
SDK_SYSTEM_TIME tmBuildTime; // the "SDK_SYSTEM_TIME" is another struct
char sSerialNumber[64];
int byChanNum;
unsigned int uiDeviceRunTime;
SDK_DeviceType deviceTye; // the "SDK_DeviceType" is a enum
}H264_DVR_DEVICEINFO,*LP_DEVICEINFO;
// this is how "SDK_SYSTEM_TIME" is defined
typedef struct SDK_SYSTEM_TIME{
int year;
int month;
int day;
}SDK_SYSTEM_TIME;
// this is how "SDK_DeviceType" is defined
enum SDK_DeviceType
{
SDK_DEVICE_TYPE_DVR,
SDK_DEVICE_TYPE_MVR,
SDK_DEVICE_TYPE_NR
};
// this is how "SocketStyle" is defined
enum SocketStyle
{
TCPSOCKET=0,
UDPSOCKET,
SOCKETNR
};
The following is their corresponding Java mappings:
public class Test implements StdCallLibrary {
public interface simpleDLL extends StdCallLibrary {
long H264_Login(String sIP, short wPort, String sUserName, String sPassword,
Structure DeviceDate, int error, int TCPSOCKET);
}
static
{
System.loadLibrary("NetSdk");
}
// the struct implementation
public static class DeviceDate extends Structure{
public SDK_SYSTEM_TIME tmBuildTime;
public String sSerialNumber;
public IntByReference byChanNum;
public IntByReference uiDeviceRunTime;
public IntByReference deviceTpye;
#Override
protected List<Object> getFieldOrder() {
List<Object> list = new ArrayList<>();
list.add("tmBuildTime");
list.add("sSerialNumber");
list.add("byChanNum");
list.add("uiDeviceRunTime");
list.add("deviceTpye");
return list;
}
}
public static class SDK_SYSTEM_TIME extends Structure{
public IntByReference year;
public IntByReference month;
public IntByReference day;
#Override
protected List<Object> getFieldOrder() {
List<Object> list = new ArrayList<>();
list.add("year");
list.add("month");
list.add("day");
return list;
}
}
// and then how I called it through the main function
public static void main(String args[]) throws FileNotFoundException{
simpleDLL INSTANCE = (simpleDLL) Native.loadLibrary( ("NetSdk"), simpleDLL.class);
DeviceDate dev = new DeviceDate() // where DeviceDate is a static class inherits com.sun.jna.Structure
int err = (int) INSTANCE.H264_GetLastError();
long result = INSTANCE.H264_Login("255.255.255.255", (short) 33333, "admin", "admin", dev, err, 0);
}
}
upon running the app, the Java crashes:
and this is the full problem signature:
Problem signature:
Problem Event Name: APPCRASH
Application Name: javaw.exe
Application Version: 7.0.600.19
Application Timestamp: 536a95c6
Fault Module Name: jna3976113557901128571.dll
Fault Module Version: 4.0.0.215
Fault Module Timestamp: 52d3949a
Exception Code: c0000005
Exception Offset: 0000e3a2 OS
Version: 6.1.7601.2.1.0.256.1
Locale ID: 1033
Additional Information 1: 7bc2
Additional Information 2: 7bc24d73a5063367529b81d28aecc01c
Additional Information 3: 5bea
Additional Information 4: 5beaa1c0441c3adb156a170a61c93d19
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Answer 1

Your mappings have a number of errors. Your structures should look like the following (IntByReference represents places where you would pass the address of an int, and you can't substitute String for a primitive native char array). Please refer to the JNA mapping documentation to ensure you understand how native types map to Java types:
public static class LP_DEVICE_INFO extends Structure{
public SDK_SYSTEM_TIME tmBuildTime;
public byte[] sSerialNumber = new byte[64];
public int byChanNum;
public int uiDeviceRunTime;
public int deviceType; // Assuming the size of the enum is int
#Override
protected List<Object> getFieldOrder() {
List<Object> list = new ArrayList<>();
list.add("tmBuildTime");
list.add("sSerialNumber");
list.add("byChanNum");
list.add("uiDeviceRunTime");
list.add("deviceTpye");
return list;
}
}
public static class SDK_SYSTEM_TIME extends Structure{
public int year;
public int month;
public int day;
#Override
protected List<Object> getFieldOrder() {
List<Object> list = new ArrayList<>();
list.add("year");
list.add("month");
list.add("day");
return list;
}
}